JPH05164271A - Method for laying flexible riser - Google Patents

Abstract

PURPOSE:To protect a flexible riser against damage resulting from the overlapping, tangling, colliding and hitting of curved slack sections with each other due to oscillation, when the riser is laid in the sea from the hull of a marine floating facility. CONSTITUTION:The curved slack sections (a) and (b) of a flexible riser 5 laid in the sea from the hull of a marine floating facility 1 are provided with a flexible supporter 10 having an oblique notch on the lower side thereof. When the sections (a) and (b) are further curved sharply, due to the oscillation of the flexible riser 5, the supporter 10 is also curved together and bent beyond curvature plane. As a result, the sections (a) and (b) are relocated outside the curvature plane, thereby being protected against overlapping, tangling, colliding and hitting with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible riser for connecting floating equipment moored on the sea and undersea equipment.

[0002]

2. Description of the Related Art Floating production equipment such as semi-sub, single-point mooring tankers are often used as equipment for refining crude oil produced from offshore offshore oil fields at sea. Since it moves on the sea surface, a flexible riser, which is a flexible fluid oil pipe with a composite structure consisting of plastic pipes and metal reinforcing strips, is often used in the pipeline that connects this to the wellhead of the submarine oil field. In order to prevent unreasonable stress from being applied to the flexible riser due to the swing of the equipment, a flexible swell is formed by a buoy so that the flexible riser bends greatly in the sea. In addition, Japanese Patent Application No. 1-
In the invention of 280580, a flexible riser line is proposed in which a plurality of curved slack portions in the sea are laterally formed to absorb the movement of the floating equipment when the movement of the floating equipment is large relative to the water depth. ing.

[0003]

When a plurality of underwater curved slack portions are formed as described above, it is possible to easily absorb a large movement of the floating equipment on the sea to the distance, but the floating equipment has a flexible riser. In the case of approaching the bottom point of the above, the curved slack portions may overlap with each other, and the flexible riser or buoy may be entangled, or may collide and hit each other, resulting in serious damage.

It is an object of the present invention to provide a flexible riser laying system for preventing overlapping, entanglement, collision and hitting of curved slack portions when the flexible riser rocks in the sea. is there.

[0005]

In order to achieve the above-mentioned object, the present invention provides a flexible riser 5 laid in the sea from the floating floating equipment 1 to the seabed.
c and a plurality of curved slack portions such as the lower curved slack portions b and d, and a plurality of oblique notches 14 on the lower surface side, and when curved, the curved surface can be bent out of the plane. The flexure supporting member 10 is attached to at least one of the curved slack portions.

[0006]

When the flexible riser having the flexible supporting member attached to the upper curved slack portion swings in the sea and the curved slack portion is further curved so that the curvature of the curved portion becomes smaller,
Along with the bending operation of the curved slack portion, the flexible supporting member is also curved, and the oblique cutout portion on the lower surface simultaneously causes three-dimensional bending in the direction of the curved surface out of the plane, so that both ends of the flexible supporting member are bent. A force is generated that twists the two in opposite directions. For this reason, both corresponding portions of the curved slack portion of the flexible riser together with the both ends of the flexible supporting member are also displaced in the opposite directions, so that overlapping of the curved slack portions, entanglement, collision, and hitting are prevented. .

[0007]

Embodiments of the present invention will be described below with reference to the drawings.
The flexible riser laying method of the present invention uses the flexible attachment member 10, an example of which is shown in the front view of FIG. 3, the cross-sectional view of FIG. 4, and the bottom view of FIG. The flexible attachment member 10 is made of an elastic material such as synthetic rubber or FRP and has oblique cutouts 14 formed in the lower surface side tube wall portion 13 ′ of the tube wall 13 of the flexible tube body 11 having a central hole 12. A plurality of them are provided, and the oblique notch 14 is 30 to 6 with respect to the central axis XX of the tubular body.
The lower surface side tube wall portion 13 ′ is formed with an appropriate inclination depth or deeply cut to reach the central hole 12 at an inclination angle θ of 0 °.

As shown in FIG. 6, the flexible auxiliary member 10 bends both ends of the flexible tubular member 11 downward, that is, in the vertical plane in the Z direction downward with respect to the central axis XX. And, due to the bending moment of this bending, the portion of the lower surface side pipe wall portion 13 'in which the plurality of slanted notches 14 on the lower side of the pipe body are provided is compressed by the compressive force P directed from both ends of the pipe to the center of the pipe. As shown in the bottom view of the tubular body of FIG. 7, a twisting force of Psin θ · cos θ acts on the oblique notch 14 of the lower side tube wall portion 13 ′. This twisting force acts in the Y direction that is lateral to the curved surface, that is, in the direction from the curved surface to the out-of-plane direction, and twists both ends of the tubular body in opposite directions in the lateral direction of the tubular body. It produces a twisting power. Thus, the lower surface side tube wall portion 1 of the lower surface of the tube body
Due to the oblique cutout 14 provided at 3 ',
When the flexible tube body 11 is bent downward in a vertical plane, three-dimensional bending outward from the curved surface occurs, and both ends of the tube body are twisted in opposite directions.

As shown in FIG. 1, the flexible attachment member 10 composed of the flexible tube body 11 having the plurality of slanted notches 14 in the lower surface side tube wall portion 13 'is floated on the sea as shown in FIG. Attached to the curved slack part of the underwater flexible riser connected to the equipment. In the figure, 1 is a floating type facility that floats on the sea surface 2. For example, a floating type production facility such as a semi-sub, one-point mooring tanker that is used as a facility for refining crude oil produced from an offshore offshore oilfield at sea. Is. This floating type equipment 1 is a target for carrying out the present invention even if it is a floating floating equipment such as a power generation device using tidal wave. 5
Is a flexible riser, which is a flexible pipe installed in the sea such as a flexible pipe for transmitting oil such as petroleum that connects the floating production facility 1 and a wellhead of a submarine oilfield, or an electric power or communication cable. It is a so-called flexible riser such as a pipe or cable. 3 is a riser base of the equipment installed at the bottom of the seabed 4 of this flexible riser terminal. Reference numeral 6 denotes a dispersion buoy composed of a plurality of buoys, which is attached to an intermediate portion of the flexible riser 5 in the sea for several tens of meters to bend and sag in the sea to form an upper curved slack portion a.
Reference numeral b denotes a lower curved slack portion which is formed in a continuous manner with the upper curved slack portion a and which is curved in an S shape.

The floating equipment floating on the sea is tidal current,
When moving over the sea due to waves or the like, the flexible riser 5 also swings in the sea along with this movement, and the curvature of the upper curved slack portion a to which the dispersion buoy 6 is attached and the lower curved slack portion b connected to the flexible buoy 6 become large and small. It changes, and in particular, the curvature of the upper curved slack portion a formed by the dispersion buoy 6 changes greatly. If the flexible support member 10 of the present invention is not attached to the flexible riser 5, when the flexible riser 5 is swung so that the curvatures of the upper and lower curved slack portions a and b become small, the flexible riser 5 is bent. There is a possibility that the parts a and b may overlap and the flexible riser or buoy may be entangled, or they may collide and strike each other, resulting in serious damage.

As described above, in order to prevent the curved slack portion of the flexible riser from colliding with the flexible riser, according to the present invention, the dispersion buoy 6 is provided.
The flexible auxiliary member 10 is attached to the vicinity of the central portion of the upper curved slack portion a to which is attached with the oblique notch portion 14 on the lower side.
The flexible attachment member 10 is mounted by inserting the flexible riser 5 into the center hole 12 of the flexible tube body 11, or by attaching the flexible tube body 11 to the outside of the flexible riser 5 with a band or the like, or Attach by appropriate means. As described above, when the flexible riser 5 in which the flexible attachment member 10 is attached to the upper curved slack portion a swings in the sea and the curvature of the curved slack portion a becomes small, the flexible riser 5 can be deformed as shown in FIGS. 6 and 7. Both ends of the flexible tube body 11 are bent downward, and both ends of the flexible tube body are twisted in opposite directions by the oblique notches 14 on the lower surface of the tube body, and both ends of the flexible tube body 11 are attached to the curved slack. Both corresponding parts of the parts are also twisted in opposite directions, and as a result, overlapping of the curved slack parts a and b, entanglement, collision, and hitting are prevented, and damage is avoided.

FIG. 2 shows a curved slack portion of the flexible riser 5, an upper curved slack portion a to which the dispersion buoy 6 is attached as in the embodiment shown in FIG. 1, and a lower curved slack portion connected to this in an S shape. Instead of forming in b, the first upper curved slack part a in which a small dispersion buoy 6 is attached for several tens of meters in the middle part of the underwater flexible riser 5 and a large buoy 7 having a buoyancy of several tons and a minimum A second upper curving slack portion c is formed laterally in the sea by a mid arch 9 having a curving surface 8 for holding the curving curvature of the upper surface, and a first S-shaped continuous portion is formed in the upper curving slack portion. In this embodiment, a lower curved slack portion b and a second lower curved slack portion d are formed. The plurality of upper curved slack portions and the lower curved slack portions thus formed can absorb the large movement amount when the movement amount of the floating equipment on the sea is large with respect to the water depth.

In the embodiment shown in FIG. 1, the flexible attachment member 10 is provided near the center of the first upper curved slack portion a to which the dispersion buoy 6 of the flexible riser 5 shown in FIG. 2 is attached. As in the case of (1), the oblique notch 14 is attached to the lower side. As the floating equipment shown in FIG. 2 moves over the sea, the flexible riser 5 swings in the sea, and the curvature of the upper curved slack portion a becomes smaller, so that the flexible tubular body 11 attached to this portion. When both ends are bent downward, both ends of the tubular body are twisted in opposite directions, and together with this, the upper curved slack portion a is also twisted in the opposite direction. By thus twisting the curved slack portions in opposite directions, the upper curved slack portions a and c, the lower curved slack portions b and d, or the curved slack portions a and b, and c. Since collisions such as d do not occur and they do not overlap in the same plane, and they do not get entangled or hit each other, damage is prevented. In addition, the flexible supporting member 10 described above.
Is not only attached to the first upper curved slack part a but also to the second
It may be attached to the lower curved slack portion d.

In FIG. 8, instead of forming the flexible supporting member 10 with a flexible pipe as in the above embodiment, a synthetic rubber, F, is used.
In this embodiment, a flexible square member 15 made of an elastic material such as RP is used, and a diagonal notch 14 similar to that in the above embodiment is provided on the lower surface of the flexible square member. Similar to the above-described embodiment, the flexible support member 10 of this flexible square member also has an upper curved slack portion a and a lower curved slack portion d of the flexible riser 5 shown in FIGS.
When the flexible riser 5 is rocked in the sea, the curved slacks are overlapped with each other, entangled or collided,
Prevents damage from hitting each other.

In the embodiment shown in FIG. 9, the flexible attachment member 10
Instead of the flexible tube body 11 made of an elastic material pipe as described above, a flexible tube body provided with a reinforcing wire 16 made of metal or FRP in the tube wall of an elastic material pipe such as synthetic rubber or FRP. 17 is an example in which an oblique notch 14 is provided on the lower surface of the tubular body in the same manner as in the above-described embodiment, and this is also the same as in the above-described embodiment, in the flexible riser 5 shown in FIGS. It is attached to the upper curved slack portion a and the lower curved slack portion d to prevent overlapping of the curved slack portions when the flexible riser 5 swings in the sea, entanglement, collision, and hitting to prevent damage.

As described above, in the flexible riser laying method of the present invention, when the flexible riser is bent so that the curvature of the curved slack portion becomes small,
A flexible auxiliary member is attached to the curved slack portion so as to prevent the curved slack portions from overlapping, entwining, colliding, or hitting each other by causing three-dimensional bending of the curvature out of the plane. As long as it is a member that causes three-dimensional bending in the curved slack portion to prevent overlapping of the curved slack portions, entanglement, collision, and beating, the above-mentioned pipe shape, square bar shape,
The present invention is not limited to the flexible tubular body configured in the shape of a pipe with a reinforcing wire, and an appropriate configuration can be adopted.

[0017]

As described above, according to the present invention, a plurality of curved slack portions are formed on a flexible riser laid in the sea from a floating floating facility, and when the curved slack portions are bent, the curved slack portion is moved out of the curved surface. Since a flexible attachment member that causes the three-dimensional bending of the curved slack portions to be displaced in the opposite directions is attached to at least one of the curved slack portions, the floating floating equipment moves on the sea surface due to tidal currents, waves, etc. However, it is possible to prevent overlapping of the curved slack portions, entanglement, collision, and hitting each other, and to prevent damage to the curved slack portions and the buoy.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a front view of an example of a flexible attachment member.

FIG. 4 is a longitudinal cross-sectional view of one embodiment of a flexible attachment member.

FIG. 5 is a bottom view of one embodiment of the flexible attachment member.

FIG. 6 is an explanatory view of a bending operation of the flexible attaching member.

FIG. 7 is an explanatory diagram of occurrence of bending of the flexible attachment member.

FIG. 8 is a view showing another embodiment of the flexible attachment member.

FIG. 9 is a view showing another embodiment of the flexible attachment member.

[Explanation of symbols]

 1; floating floating equipment 5; flexible riser 10; flexible attachment members a, b, c, d; curved slack portion

Claims (1)

[Claims] 1. A flexible riser laid in the sea from a floating floating facility is provided with a plurality of curved slack portions, and at least one of the curved slack portions is bent out of a curved surface when being bent. A flexible riser laying method, which is equipped with a flexible attachment member.